/* Copyright 2007-2008 dnAnalytics Project.
 *
 * Contributors to this file:
 * Patrick van der Velde
 *
 * This file is part of dnAnalytics.  dnAnalytics is licensed under the 
 * Microsoft Public License. See License.txt for a complete copy of the
 * license.
 */

using System;
using System.Diagnostics;
using dnAnalytics.LinearAlgebra;
using dnAnalytics.LinearAlgebra.Solvers;
using dnAnalytics.LinearAlgebra.Solvers.Preconditioners;
using NUnit.Framework;

namespace dnAnalytics.Tests.LinearAlgebra.Solvers.Preconditioners
{
    public abstract class PreconditionerTest
    {
        protected const double s_Epsilon = 1e-10;

        internal SparseMatrix CreateUnitMatrix(int size)
        {
            SparseMatrix matrix = new SparseMatrix(size);
            for (int i = 0; i < size; i++)
            {
                matrix[i, i] = 2;
            }
            return matrix;
        }

        protected Vector CreateStandardBcVector(int size)
        {
            Vector vector = new DenseVector(size);
            for (int i = 0; i < size; i++)
            {
                vector[i] = i + 1;
            }
            return vector;
        }

        internal abstract IPreConditioner CreatePreconditioner();

        protected abstract void CheckResult(IPreConditioner preconditioner, SparseMatrix matrix, Vector vector, Vector result);

        [Test]
        public void ApproximateWithUnitMatrixReturningNewVector()
        {
            int size = 10;
            SparseMatrix newMatrix = CreateUnitMatrix(size);
            Vector vector = CreateStandardBcVector(size);

            IPreConditioner preconditioner = CreatePreconditioner();
            preconditioner.Initialize(newMatrix);

            Vector result = preconditioner.Approximate(vector);

            CheckResult(preconditioner, newMatrix, vector, result);
        }

        [Test]
        public void ApproximateReturningOldVector()
        {
            int size = 10;
            SparseMatrix newMatrix = CreateUnitMatrix(size);
            Vector vector = CreateStandardBcVector(size);

            IPreConditioner preconditioner = CreatePreconditioner();
            preconditioner.Initialize(newMatrix);

            Vector result = new DenseVector(vector.Count);
            preconditioner.Approximate(vector, result);

            CheckResult(preconditioner, newMatrix, vector, result);
        }

        [Test]
        [ExpectedException(typeof(NotConformableException))]
        public void ApproximateWithVectorWithIncorrectLength()
        {
            int size = 10;
            SparseMatrix newMatrix = CreateUnitMatrix(size);
            Vector vector = CreateStandardBcVector(size);

            IPreConditioner preconditioner = CreatePreconditioner();
            preconditioner.Initialize(newMatrix);

            Vector result = new DenseVector(vector.Count + 10);
            preconditioner.Approximate(vector, result);
        }

        [Test]
        [ExpectedException(typeof(ArgumentNullException))]
        public void ApproximateWithNullVector()
        {
            int size = 10;
            SparseMatrix newMatrix = CreateUnitMatrix(size);
            Vector vector = CreateStandardBcVector(size);

            IPreConditioner preconditioner = CreatePreconditioner();
            preconditioner.Initialize(newMatrix);

            Vector result = new DenseVector(vector.Count + 10);
            preconditioner.Approximate(null, result);
        }

        [Test]
        [ExpectedException(typeof(ArgumentNullException))]
        public void ApproximateWithNullResultVector()
        {
            int size = 10;
            SparseMatrix newMatrix = CreateUnitMatrix(size);
            Vector vector = CreateStandardBcVector(size);

            IPreConditioner preconditioner = CreatePreconditioner();
            preconditioner.Initialize(newMatrix);

            Vector result = null;
            preconditioner.Approximate(vector, result);
        }

        [Test]
        [ExpectedException(typeof(MissingMatrixException))]
        public void ApproximateWithNonInitializedPreconditioner()
        {
            int size = 10;
            SparseMatrix newMatrix = CreateUnitMatrix(size);
            Vector vector = CreateStandardBcVector(size);

            IPreConditioner preconditioner = CreatePreconditioner();

            Vector result = preconditioner.Approximate(vector);
        }
    }
}